The present disclosure relates in general to electric motors. More specifically, this relates to the reduction of torque ripple in an electric motor.
Electric motors are used in many different applications. Existing electric motors can suffer from undesirable harmonics that effect the operation of the electric motor. There are various different causes of harmonics. For example, offset and gain error in current measurement separately causes the first and second harmonic in the drive and motor system. The amplitude and spatial error in the motor construction and the imbalance in the utility power system can both contribute to sixth harmonics. The result of harmonics can create torque ripple, which can be detrimental to the object being driven by the electric motor, causing unevenness in the object being driven. In essence, torque ripple is a variation in the torque being provided by an electrical motor. Torque ripple can be particular objectionable when people are being driven by electric motors, such as in vehicles, elevators, escalators, and the like, especially in situations in which the variations can be amplified by the device being driven.